Turbo charging an engine allows the engine to provide power similar to that of a larger displacement engine while engine pumping work is maintained near the pumping work of a normally aspirated engine of similar displacement. Thus, turbo charging can extend the operating region of an engine. However, during conditions where there is low flow through a compressor of the turbocharger and a high pressure ratio across the compressor, the compressor speed may surge and cause noise or other undesirable responses. Compressor surge may be mitigated via an electrically operated compressor bypass valve (CBV). In particular, the CBV may be opened to allow air to flow from the compressor outlet to the compressor inlet so as to reduce the pressure ratio across the compressor. The electrically operated CBV may be commanded open when compressor surge conditions are approached. For example, the CBV may be opened when an operator releases a torque command actuator (e.g., an accelerator pedal) and the engine throttle is closed to reduce engine torque. The electrically operated CBV may reduce the possibility of compressor surge; however, the electrically operated CBV requires a controller with executable code to open the electrically operated CBV at proper timing. Further, additional electronics may be needed to operate the CBV. Further still, the CBV can add cost to the turbocharged engine.
The inventors herein have recognized the above-mentioned disadvantages and have developed a system for reducing the possibility of turbocharger compressor surge, comprising: an engine throttle valve responsive to an engine torque command; and a compressor bypass valve in mechanical communication with the engine throttle.
In this way, the possibility of turbocharger compressor surge may be reduced without incurring additional system cost for electronics and code to operate a compressor bypass valve. In one example, a compressor bypass valve may be configured as a butterfly valve operated via a shaft that operates the engine throttle which controls air flow to the engine. In another example, the compressor bypass valve may be configured as a poppet valve operated via a cam that is rotated via a shaft that adjusts a position of a throttle valve. Thus, the compressor bypass valve may be operated via the same electronics that operate the engine throttle.
The present description may provide several advantages. In particular, the present description may simplify operation of the compressor bypass valve as it may be operated via the engine throttle actuator. Further, the present description may reduce system cost since the compressor bypass valve may be operated via the same electronics as the engine throttle. Further still, additional computer code for operating the compressor bypass valve may not be necessary. Consequently, additional time may be available for the engine controller to operate other actuators and monitor other system inputs.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.